The pale light increased.  The electrics seemed to dim and fade.  Tom looked to the engines.  Some of the apparatus was in need of oil, and he supplied it.  When he came back to the main cabin, where stood Mr. Damon and Mr. Fenwick, it was much lighter outside.

“Less than a day since we left Philadelphia,” murmured the owner of the whizzer, as he glanced at a distance indicator, “yet we have come nearly sixteen hundred miles.  We certainly did travel top speed.  I wonder where we are?”

“Still over the ocean,” replied Mr. Damon, as he looked down at the heaving billows rolling amid crests of foam far below them.  “Though what part of it would be hard to say.  We’ll have to reckon out our position when it gets calmer.”

Tom came from the engine room.  His face wore a troubled look, and he said, addressing the older inventor: 

“Mr. Fenwick, I wish you’d come and look at the gas generating apparatus.  It doesn’t seem to be working properly.”

“Anything wrong?” asked Mr. Damon, suspiciously.

“I hope not,” replied Tom, with all the confidence he could muster.  “It may need adjusting.  I am not so familiar with it as I am with the one on the Red cloud.  The gas seems to be escaping from the bag, and we may have to descend, for some distance.”

“But the aeroplanes will keep us up,” said Mr. Daman.

“Yes—­they will,” and Tom hesitated.  “That is, unless something happens to them.  They are rather frail to stand alone the brunt of the gale, and I wish—­”

Tom did not complete the sentence.  Instead, he paused suddenly and seemed to be intently listening.

From without there came a rending, tearing, crashing sound.  The airship quivered from end to end, and seemed to make a sudden dive downward.  Then it appeared to recover, and once more glided forward.

Tom, followed by Mr. Fenwick, made a rush for the compartment where the machine was installed.  They had no sooner reached it than there sounded an explosion, and the airship recoiled as if it had hit a stone wall.

“Bless my shaving brush!  What’s that?” cried Mr. Damon.  “Has anything happened?”

“I’m rather afraid there has,” answered Tom, solemnly.  “It sounded as though the gas bag went up.  And I’m worried over the strength of the planes.  We must make an investigation!”

“We’re falling!” almost screamed Mr. Fenwick, as he glanced at the barograph, the delicate needle of which was swinging to and fro, registering different altitudes.

“Bless my feather bed!  So we are!” shouted Mr. Damon.  “Let’s jump, and avoid being caught under the airship!”

He darted for a large window, opening from the main cabin, and was endeavoring to raise it when Tom caught his hand.

“What are you trying to do,” asked the lad, hoarsely.

“Save my life!  I want to get out of this as soon as I can.  I’m going to jump!”